The primary objectives of this research program are to investigate the in vitro and in vivo mode of avian retravirus proviral DNA synthesis. These studies include: (1) determination of the NH2- and C-terminals and partial NH2-terminal amino acid sequence of purified avian myeloblastosis virus (AMV) alpha and beta DNA polymerase subunits as well as that of the other purified primary cleavage product of the beta subunit, AMV p32: (2) defining the in vivo phosphorylated state of AMV p32; (3) identification of a temperature-sensitive DNA endonuclease activity associated with purified alphabeta DNA polymerase isolated from avian retravirus ts-mutants; (4) further characterization of the AMV p32 and alphabeta DNA polymerase-associated DNA endonuclease activities; (5) investigate the mechanisms involved in double-stranded viral DNA synthesis; and RNase H activity; (6) determining the effect of AMV p32 on proviral DNA synthesis; (7) identification of a 30,000 dalton DNA-binding protein derived from the DNA polymerase of mammalian retraviruses; (8) analysis of precursor polypeptides in the biosynthesis of avian retravirus DNA polymerase subunits and p32; (9) defining the mechanisms involved in in vivo proviral DNA formation and integration; and (10) DNA sequencing of cDNA synthesized from mouse myeloma immunoglobulin mRNAs by AMV alphabeta DNA polymerase.